JP2005523845A - Thermoplastic containers for products that need to be protected from light - Google Patents

Abstract

The present invention relates to containers such as bottles, flasks, tanks or the like for containing products that need to be protected from light, said containers being made from a thermoplastic material and blowing or pulling preforms. Manufactured by blow, the container is characterized in that the container comprises a layer of thermoplastic material uniformly mixed with 2-4 wt% mica flakes with the addition of 2-4 wt% titanium oxide powder. Is to have.

Description

  The present invention relates to improvements made to containers, such as bottles, flasks, cans or the like, intended to contain products that must be protected from light, these containers being made of thermoplastic, Manufactured by blow molding or stretch blow molding of foam.

  Certain products are adversely affected by the action of light.

  Whether the light is natural light or very rare but artificial light, the light changes the taste, especially in the case of milk.

This affected taste, known as “light taste”, appears in two forms:
・ “Activated taste” (cabbage taste, casual taste or mushroom taste) that appears very quickly,
・ Oxidizing taste that gradually develops (cardboard, paper, metal or oil taste).

These unpleasant tastes are caused by several phenomena. :
• Degradation of amino acids and proteins, especially methionine, which is the main cause of “activated” taste;
The conversion of vitamins, particularly the loss of water-soluble vitamins such as riboflavin, and the degradation of fat-soluble vitamins such as retinyl, which are one of the causes of "activated"taste;
-Palmitate (vitamin A) at wavelengths shorter than 450 nm;
• Oxidation of unsaturated fatty acids, which is the main cause of oxidized taste.

  The effect of light also depends on the treatment that the milk receives.

Finally, the beginning of the unpleasant taste of milk depends on several parameters:
・ Amount of light received by milk (light intensity and exposure time)
• Wavelength of radiation • Sensitivity of the product itself • Temperature In particular, the taste of light seems to be caused substantially by radiation of wavelengths shorter than 550 nm in the visible and ultraviolet range windows respectively. The International Milk Federation therefore recommends the use of packaging that transmits only 2% of 400 nm light and 8% of 500 nm light.

  Finally, the packaging material thickness and the volume / surface area ratio also affect the onset of bad taste.

  It will be readily apparent from the foregoing description that the time that milk or dairy products are stored can be extended if protection against light is made more effective.

  The test was performed on colored bottles. This resulted in better preservation of milk than clear or translucent bottles, but was not proven to give milk a better shelf life under the required conditions.

  A very widely used solution for selling long-lived milk is to make a multi-layer container made of three or more thin thermoplastic materials (eg HDPE) laminated together. At least one of the inner layers of this multilayer is mixed with pigments to make it opaque to light (long life bottle with black inner layer). This allows the shelf life to be met by the conditions required by the market. A similar solution can also be applied to PET: however, in this case, the production of the initial preform is very complex and expensive; in addition, delamination can subsequently occur.

  In general, known methods currently used or considered are complicated to implement, in the case of PET it is uneconomical and very complex.

  Therefore, users (containers and packaging producers) provide products with effective protection against the effects of light and are made of thermoplastics that are easier to manufacture and less expensive than the containers currently in use. There is an urgent need for containers of polyethylene terephthalate PET, polyethylene naphthalate PEN, high density polyethylene HDPE, and the like.

  For these reasons, the invention is characterized in that it comprises a layer of thermoplastic in which 2-4% by weight level of mica flakes are uniformly mixed with the addition of 2-4% by weight level of powdered titanium oxide. Propose a container as described in the introduction.

  In accordance with a preferred embodiment of the present invention, the container is made of a single layer of mixed plastic material forming the aforementioned layers, which makes the container manufacturing process simpler and less costly. However, at least for some uses, the embodiment is comprised of a container that is externally covered with a sleeve that tightens it, and that the sleeve is made of a mixed thermoplastic material that constitutes the aforementioned layer. The invention is not excluded.

  By hand according to the present invention, the light barrier effect is provided to a certain extent by the mica pigment alone and to a lesser extent by the titanium oxide powder alone. In contrast, a particularly effective effect is obtained with the combination of mica pigment and titanium oxide powder. This light barrier effect is particularly evident for wavelengths shorter than about 550 nm, ie for radiation that plays the largest role in the milk degradation process.

  The light barrier effect is provided by the entire mica microflakes that are dispersed within the thermoplastic material to form a physical barrier to light propagation, so that these microflakes are continuous so that the desired effect can be achieved. It must be present in an amount sufficient to allow the barrier to be formed.

  On the other hand, however, the presence of the mica fine flakes (which are thermal insulators) can interfere with the heating of the thermoplastic material if the layer is being produced. Also, if the container is made of a single layer, it is absolutely essential that the preform can be properly heated prior to the blow molding or stretch blow molding process, and also the amount of mica microflakes filled is It must also be present in a proportion that does not interfere with the proper progress of the blow molding or stretch blow molding process therein.

  Similarly, excessive proportions of titanium oxide powder should be avoided due to the subsequent obstacles during the concentration of the heated plastic paste and the manufacture of the container.

  The proportion that the sum of the two additives does not exceed about 8% by weight appears to satisfy these contradictory requirements well.

  Finally, both mica pigment and titanium oxide are products that are desirable to be introduced into thermoplastic materials in minimal amounts so that the container does not change the mechanical properties for the manufacture and use of the container. It is. In order to meet this requirement, preferably the proportion of each mica is about 2 so that the combination is limited to about 4% by weight, while at the same time following the above-mentioned constraints aimed at not disrupting the container manufacturing method. Preparations are made so that titanium oxide is present at a level of ˜4 wt%, titanium oxide at a level of about 2-4 wt%. Usually, desirable results are obtained by preparing the mica to be present at about 2% by weight and titanium oxide at about 2% by weight.

  More specifically, the light barrier effect is optimized when all the micro flakes of mica are partially overlapped and arranged parallel to each other and parallel to the wall surface of the container (arranged like a roof tile). This makes it possible to ensure that there is no straight path through the thickness of the container wall where light can reach the product contained in the container.

  In particular, in the case of single layer containers, the necessary positioning of the fine flakes is during the blow molding or stretch blow molding process that the thermoplastic preform must undergo due to the formation of bi-directional molecules in the final container. Naturally obtained: Double stretching (axial and radial) resulting in bi-orientation simultaneously directs roof tile styles that require fine flakes, thereby taking into account different processing steps to achieve this There is no need to do anything.

  A hand in accordance with the present invention finds a preferred application in the production of containers in which the light barrier layer is obtained with a thermoplastic material selected from polyethylene terephthalate PET, polyethylene naphthalate PEN and high density polyethylene HDPE.

  As already apparent from the foregoing description, the present invention is a non-exclusive and non-limiting mica that forms a barrier to light that allows it to be stored for a sufficiently long time without compromising the taste of milk. It is intended for a particularly beneficial application of milk bottles made of a PET single layer mixed with flakes and titanium oxide powder. Typically, bottles made from a PET single layer with 2% by weight mica and 2% by weight titanium oxide can store long-lived milk for longer than the three months required by law under average storage conditions To.

  Also, as is apparent from the foregoing description, the present invention is not limited to the field of preservation of milk or dairy products, but may find use in the storage of other products that are unstable to light, such as oils, particularly olive oil or beer. it can.

Claims (7)

  Containers such as bottles, flasks, cans or the like that are made of thermoplastics and are manufactured by blow molding or stretch blow molding of preforms and are intended to contain products that need to be protected from light. The container includes a thermoplastic layer in which mica flakes are uniformly mixed at a level of 2 to 4% by weight with addition of powdered titanium oxide at a level of 2 to 4% by weight.   A container according to claim 1, characterized in that the container consists of a single layer of mixed plastic material forming the layer.   2. A container according to claim 1, characterized in that the container is made of a mixed thermoplastic that is covered with a sleeve that grips it on the outside and that constitutes the layer.   The mica is present in a proportion to a level of about 2 to 4% by weight and the titanium oxide is present in a proportion to a level of about 2 to 4% by weight, so that the combined amount represents about 4% by weight. The container of any one of thru | or 3.   5. A container according to claim 4, characterized in that mica is present at a level of about 2% by weight and titanium oxide is present at a level of about 2% by weight.   The container according to any one of claims 1 to 5, characterized in that the thermoplastic is selected from polyethylene terephthalate PET, polyethylene naphthalate PEN, and high density polyethylene HDPE.   A milk bottle formed as described in any one of claims 1 to 6.